: a phosphoprotein of milk: such as
a
: one that is precipitated from milk by heating with an acid or by the action of lactic acid in souring and is used in making paints and adhesives
b
: one that is produced when milk is curdled by rennet, is the chief constituent of cheese, and is used in making plastics
Examples of casein in a Sentence
Recent Examples on the Web
Avoid those with beeswax or casein, a milk product sometimes used in paint.
—
Paige Porter Fischer, Better Homes & Gardens, 22 Apr. 2025
Common sources include: Whey or casein: These are complete proteins derived from milk.
—Morgan Pearson, Ms, Rd, Verywell Health, 18 Apr. 2025
Milk contains whey and casein proteins, which stimulate muscle growth.
—Jillian Kubala, Health, 15 Apr. 2025
An allergic reaction to milk happens when the immune system reacts against proteins in the milk, such as casein and whey.
—Yaakov Katz, Newsweek, 17 Jan. 2025
See All Example Sentences for casein
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Paige Porter Fischer, Better Homes & Gardens, 22 Apr. 2025
Common sources include: Whey or casein: These are complete proteins derived from milk.
—Morgan Pearson, Ms, Rd, Verywell Health, 18 Apr. 2025
Milk contains whey and casein proteins, which stimulate muscle growth.
—Jillian Kubala, Health, 15 Apr. 2025
An allergic reaction to milk happens when the immune system reacts against proteins in the milk, such as casein and whey.
—Yaakov Katz, Newsweek, 17 Jan. 2025
See All Example Sentences for casein
Cite this Entry
“Casein.” Merriam-Webster.com Dictionary, Merriam-Webster, https://www.merriam-webster.com/dictionary/casein. Accessed 2 May. 2025.
Copy CitationKids Definition
casein
noun
ca·sein
ˈkā-ˌsēn 
kā-ˈsēn
1
: a phosphorus-containing protein that is separated from milk especially by the action of acid that is used in making paints and adhesives
2
: a phosphorus-containing protein that is produced when milk is made to form curds by rennet, that makes up a major part of cheese, and that is used in making plastics
Medical Definition
casein
noun
ca·sein
ˈkā-ˌsēn, ka-ˈsēn
: any of several phosphoproteins of milk: as
a
: one that occurs as a colloidal suspension in milk
called also caseinogen
b
: one that is produced when milk is curdled by rennet, is the chief constituent of cheese, and is used in making plastics
called also paracasein
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